Manufacturers are particularly concerned that high quality products portray a high quality image. To this end, identifying labels are preferably made of high quality material and attached to the product in a high quality manner. In the mattress field, for example, mattress companies have specifications regarding the appearance and the attachment of the label. Among these is the requirement that the outer edge of the label must be securely sewn to a top panel of the mattress. In addition, the label should not have trim tails or other unsightly features.
To date, attaching labels to quilted mattresses has been particularly troublesome. Attempts have been made to use top-of-the-line programmable X-Y sewing machines, e.g., Mitsubishi No. PLK A 3040, to implement a commercially acceptable attachment of labels to thick, puffy, or quilted materials, such as quilted mattress panels. These machines, however, fail to provide an acceptable cost/performance ratio for the mattress construction field.
Attempts have also been made to sew labels to thick, puffy, or quilted materials, using less expensive programmable sewing machines, such as using 360.degree. clamping machines having a bottom plate and an upper frame. Panels are placed face-side-up and then clamped down. The upper clamp includes a window to hold the label. The panel and label are then sewn together.
These attempts have proved inadequate for quilted mattress panels, in particular, because the clamping action forms an uneven surface under the label, i.e., a "concave effect." Because of the concave effect, the label cannot be held in place properly, even if an extra stage of depressing the label is used. The label gets bunched, possibly misaligned, and appears unsightly.
Two stage clamping methods and apparatus have also been attempted. The panel is placed face-side-up, and a first stage of clamping holds the quilted panel. The label is then placed, and a second stage of clamping captures the edge of the label, approximately 1/16 of an inch in from the label edge. Though the label is held relatively securely, stitching can only be performed inwardly of the second stage clamp. Consequently, the peripheral edge is not sewn down. Though these machines offer slightly more control over the label placement than the 360.degree. clamping machines, described above, they produce a commercially unacceptable product, because the labels are unattached at the peripheral edges.
Adhesive techniques have also been attempted. The label is first glued to the mattress panel, then later stitched. These methods increase the manufacturing cost, because they involve extra handling and because the use of adhesive materials requires improved ventilation systems and the like.
Moreover, many of the methods and machines, described above, are difficult to use in the field of mattress construction because of the extra weight and thickness of the materials involved in mattress construction. Thick and puffy panels are more difficult to load and unload in a machine than are thin fabrics. Complicating this problem, standard machines do not begin operation with the needle in a position providing the maximum needle clearance. Rather, prior art machine start operation with the take up lever at top dead center. On the Mitsubishi No. PLK A 4516, for example, this position places the needle 5/16 of an inch below maximum clearance. In addition, the PLK A 4516 monitors the shaft position with an encoder, and if the shaft is rotated more than 6.degree. from the start position, the encoder sends a reset signal to a controller of the machine.
As such, there is a need in the art for a cost effective label stitching machine that can sew labels to thick, puffy, or quilted materials, such as a quilted mattress panel, in a high quality manner.
There is also a need in the art for a label stitching method and apparatus in which the label can be sewn, without bunching, and in a reliable, high quality manner.
There is also a need in the art for a label stitching method and apparatus that sews the labels to quilted mattress panels without leaving unsightly trim tails.
There is also a need in the art for a label stitching method and apparatus in which the materials may be easily loaded and removed from the apparatus.